An important approach for HIV/AIDS prevention is to diagnose co-infections that significantly increase the transmission of HIV. In this proposal, we propose to develop a rapid point-of-care (POC) test that simultaneously diagnoses HIV-1 and two sexually transmitted infections (STI's). Syphilis and genital herpes are STI's that enhance HIV transmission;if diagnosed, they can be cured with low-cost and effective treatment. The link between syphilis and HIV transmission is well-established, and the effectiveness of suppressing genital herpes to reduce HIV acquisition and transmission are being tested in two phase III trials. The overall goal of this NIAID STTR Advanced Technology project is to test the hypothesis that simultaneous, point-of-care (POC) testing of patients with HIV-1 and STI co-infections can lead to lower incidence of HIV/AIDS. The goal of Phase I is to take the first step of this work, by establishing the technical feasibility of developing a high-performing but extremely low-cost POC, multiplexed, diagnostic test for HIV-1 and STI's. We will target the design for two settings of final use: sexually transmitted disease (STD) clinics in underserved U.S. communities, and because of its extreme low cost, in health clinics in developing countries. The technology behind this STTR proposal is based on our previously developed technologies for detecting protein markers (specifically, anti-HIV-1 antibodies) from human serum. These lab-on-a-chip devices exhibited an unprecedented low cost. This work was performed at Harvard University, and the pending patents have been exclusively licensed to Claros Diagnostics, a small-business company co-founded by the scientists in 2004. The specific aims for Phase I of this STTR project are: 1. To develop a lab-on-a-chip configuration with an appropriate selection of reagents for low-cost and simultaneous detection of anti-HIV-1, anti-treponemal, and anti-herpes simplex virus type-2 (HSV-2) antibodies from human whole blood. 2. To determine the flow conditions and internal standards necessary for accurate and repeatable measurements of these three antibodies in whole blood. An important approach for HIV/AIDS prevention is to diagnose co-infections that significantly increase the transmission of HIV. This proposal aims to develop a rapid point-of-care (POC) test that simultaneously diagnoses HIV-1 and two sexually transmitted infections (STI's), syphilis and genital herpes.